New growth sprouts from a mature California bay laurel tree at Codornices Park in Berkeley, Calif., on Tuesday, June 24, 2008. A study released by UC Berkeley researchers suggest that native plants in California may suffer a dramatic decrease in numbers due to global climate change.Photo by Paul Chinn / The Chronicle less

New growth sprouts from a mature California bay laurel tree at Codornices Park in Berkeley, Calif., on Tuesday, June 24, 2008. A study released by UC Berkeley researchers suggest that native plants in ... more

Photo: Paul Chinn, The Chronicle

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Woolyleaf Ceanothus is found throughout the mountains of southern California, below 5000 feet, and in the central foothills of the Sierra Nevada. Under future climates, it may be restricted to low-lying areas, most of which are already highly urbanized, but could expand across wide areas of the coast ranges as far north as Humboldt county.Michelle Cloud-Hughes / Courtesy to The Chronicle less

Woolyleaf Ceanothus is found throughout the mountains of southern California, below 5000 feet, and in the central foothills of the Sierra Nevada. Under future climates, it may be restricted to low-lying areas, ... more

Photo: Michelle Cloud-Hughes, Courtesy To The Chronicle

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The fire poppy is an annual wildflower frequently seen shortly after fires at low elevations from San Diego to the Bay Area. In the future, it is projected to disappear in most areas south of Ventura, and shift towards the coast and northwards past the Bay Area.Christopher Christie / Courtesy to The Chronicle less

The fire poppy is an annual wildflower frequently seen shortly after fires at low elevations from San Diego to the Bay Area. In the future, it is projected to disappear in most areas south of Ventura, and shift ... more

Photo: Christopher Christie, Courtesy To The Chronicle

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A lone park visitor walked beneath the towering redwoods on the main trail at Muir Woods Tuesday, June 10, 2008. Muir Woods has been called one of the quietest parks in the nation by the Coalition of National Park Services. less

A lone park visitor walked beneath the towering redwoods on the main trail at Muir Woods Tuesday, June 10, 2008. Muir Woods has been called one of the quietest parks in the nation by the Coalition of National ... more

Photo: Brant Ward, The Chronicle

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California bay laurel. Chronicle graphic by John Blanchard

California bay laurel. Chronicle graphic by John Blanchard

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Interior Live Oak. Chronicle graphic by John Blanchard

Interior Live Oak. Chronicle graphic by John Blanchard

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Grim look at state's plant life

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If temperatures rise rapidly in California this century, up to two-thirds of the state's native plants might lose large swaths of suitable habitat, according to a new study.

Scientists from UC Berkeley, Duke University and other institutions released maps Tuesday showing how 2,300 plants found only in the state might respond to the effects of global warming.

"The pace of climate change in the next 100 years poses a very serious threat to California's native plants," said David Ackerly, a UC Berkeley biology professor and an author of the new study published in the PLoS One, the Public Library of Science.

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Scientists know that plants can respond to changing climate over thousands of years, Ackerly said. "But in less than a century, there is very little chance for plants to establish new populations and to migrate to keep up with these dramatic changes."

Over the past few decades, climate scientists have found that plants respond to rising temperatures by climbing to higher elevations seeking a cooler climate. The movement can be north or south, depending on the mountain ranges.

Yet plants die when they reach mountaintops and can't move any higher, scientists have found. Movement is also hampered by loss of habitat and competition from invasive species.

According to NASA, surface temperatures rose almost 1 1/2 degrees Fahrenheit in the past century, but much of that was in the past 50 years. Eleven of the past 12 years (1995-2006) are the warmest since accurate record-keeping began in 1850.

California is known for its Mediterranean climate of hot, dry summers and cool, wet winters. Most susceptible to species loss would be the foothills of the northern Sierra Nevada, the study found. In contrast, the researchers found that the central coast from the Big Sur region up into Mendocino County would remain rich in plant life even if most plants couldn't migrate. If plants could migrate and establish new populations, they might spread north up to southern Oregon, where diversity could expand.

The authors of the study say they cannot predict the fate of any specific species. However, their work included focusing heavily on nearly 600 of the most-studied native plants, including the live oak, blue oak, scrub oak, California bay laurel, whiteleaf manzanita and the San Francisco wallflower.

Scientists said they could not collect enough data to accurately predict what may happen to California's most iconic tree - the redwood. They lacked the fog forecasts under global warming models that would help project the movement of the coastal trees. But the authors noted that the big established redwoods and oaks might be saved.

"They may become the living dead," said Ackerly. "The old ones will remain but the seedlings won't grow. All it does is forestall the inevitable."

The analysis was based on two climate models looking at carbon dioxide levels from lower- and higher-emissions scenarios. Some of the information on plant location was obtained from databases containing tens of thousands of specimens, some gathered from institutions including the California Academy of Sciences and the Jepson Herbarium at UC Berkeley.

If emissions continue at their current rate and carbon dioxide concentrations hit 970 parts per million in the atmosphere in the period from 2080-2099, the study found that up to 66 percent of plants would disappear from 80 percent or more of their present ranges.

But if the emissions drop to below 1990 levels by the end of the century, researchers predict carbon dioxide concentrations would reach 550 parts per million. At that level, the authors of the study said the impact would be much less on native plants.

At present, levels are 387 parts per million, up almost 40 percent since the Industrial Revolution and the highest for at least the past 800,000 years.

If plants are able to move rapidly in the next 100 years, they would have to move an average of up to 95 miles to keep up with changing climate. The plants could move in different directions, potentially breaking up familiar California native plant associations, the authors said.